I see it this way:

The part about playing second Mox Opal and returning it to the top with Academy Ruins is a loop. You don't advance the game state, as you end up having the same exact position as the previous turn. You need to give a number of iterations (mostly irrelevant, since your opponent can't do anything) and finish the loop by choosing another action.

The part about drawing a new card, however, is not a loop. You end up with (potentially, and probably) new cards, you are changing the game state (indeed, if for some reason you end up not able to cast your cards, that Platinum Angel might even attack!!) and nothing forces you to reveal the information about not having a single response to your opponent. Neither the judge should, by “forcing you to concede”, reveal that information to your opponent. We've never ruled that in the past (from other “simpler” situations with MonoU Tron).

TL;DR: You can't go on and on with the Mox Opal trick, but you have the right to draw your deck one at a time, providing you do it in a reasonable time frame. Yes, this means that if there are a few minutes left only in the clock, you probably will win without any Stalling problems (in the extra turns, is perfectly legal eating up them with the Mox Opal trick, since you're not bounded anymore by time but turns). If there is more time left, your best move is to insta-concede and hope to win G3.

Originally posted by Joaquín Pérez:

(in the extra turns, is perfectly legal eating up them with the Mox Opal trick, since you're not bounded anymore by time but turns).

Playing slowly in Additional Turns is still illegal. We do not differentiate between time when the clock is running and when it has stopped.

I think that Joaquín was referring to eating up the 5 extra /turns/, without necessarily playing slowly. Stalling also requires a time limit that you're taking advantage of (although, it isn't always the round clock!) It's certainly legal to play for the draw, as long as you're neither taking more time than necessary for game actions, or falling on the wrong side of the loop rules.

Originally posted by Joaquín Pérez:

TL;DR: You can't go on and on with the Mox Opal trick, but you have the right to draw your deck one at a time, providing you do it in a reasonable time frame.

While this is true, a reasonable time frame can take into account the current game state. Assuming I'm at the table watching this match, I expect each decision about a drawn card to take no more than 5 seconds. Since we are stable with the opponent decked, that's probably only going to buy the Lantern player around 3 minutes.

(Of course, a normal Lantern deck should have no problem killing a Platinum Angel with access to its full 60, so let's hope the judge doesn't need to get involved at all.)

I disagree that this is a loop. I'd suggest to the players that they consider a draw, but otherwise, carry on.

Edit: Toby says it's a loop. It's a loop.

Edited Olivier Jansen (Sept. 2, 2016 07:53:32 PM)

Originally posted by Olivier Jansen:

I disagree that this is a loop. I'd suggest to the players that they consider a draw, but otherwise, carry on

Out of interest - what makes you disagree?

On the GP I had a Seal of Primordium and a Nature´s Claim, but both were already in the graveyard when the Angel was still in hand. He could have used a Relic of Progenitus and exiled the graveyard before I had the chance to return to my hand.

I woudln't call it a loop either. Especially since all discussion about loops include “You need to state how many times you are repeating it” but it isn't actually repeatable. The player CANNOT say “I will do this five hundred times” they can't even say “I'll do this twice” because it is something they can only do once per turn.

Now Academy Ruins is tapped, which is a change in the game state. Now I pass the turn to my opponent which is definitely a change in the game state. The problem with

1. Activate Academy Ruins on your end step.
2. Draw Mox
3. Play Mox
4. Pass the turn.
Repeat ad infinitum.

Is that Step 4 does not actually go to step 1. After step 4 is several steps of the opponent going into their draw step, trying to draw a card, having Platinum Angel prevent their losing, a bunch of passes of priority and then ending -their- turn. The opponent is in just as much of a loop, it goes like this:

1. Fail to draw a card
2. Fail to lose the game due to Platinum Angel
3. Pass the turn
Repeat ad infinitum

Why is their identical loop of actions fine, but the Lantern player's identical loop of actions not fine?

You are under no obligation to let an opponent win who cannot lose. That's like saying if an opponent gains infinite life, and you don't have a source of infinite damage, you should just concede. They putting themselves in a position where they can't lose is not the same thing as winning. They are still obliged to actually defeat you, and if they can't, the game should rightly end in a draw.

If the Lantern Control player had a card in play that allowed him to simply skip his draw step, so he could just pass the turn every time his opponent did, would that still be “slow play”? Would that be a repeatable loop? It contains 0 actions. They simply start their turn, and end their turn. In that case both players are just passing the turn back and forth over and over and neither player is changing the game state (of course that's also what is happening with the Mox/Ruins trick)

In that case one would argue the game would end in a draw, meaning the Lantern Control player wins the match.

It's a loop. The game state is being repeated, and loops can cross turn boundaries.

Only one player is taking an optional action here to sustain the loop. Ask them how many times they want to do it, then tell them to stop.

In your example the lantern player is required to take an action because he is the only one with the option to do something different

And if they draw the second game and there's still time in the round, they should start the third game, the Lantern player doesnt automatically wins

So lets expand a little bit this scenario. If I have possibility to “revive” not only Mox Opal but also Chromatic Sphere and Chromatic Star? Is it still a loop if I will change what artefact I will put on top of my library each turn?
I think in that case no, but Lantern player still just try to “eat time” there.

edit: On the other hand, I see reasoning like that: I did loop A 4 times, loop B 6 times and loop C one time and I can't then do loop A again therefore I lose.

Edited Bartłomiej Wieszok (Sept. 2, 2016 12:08:36 PM)

Originally posted by Toby Elliott:

It's a loop. The game state is being repeated, and loops can cross turn boundaries.

Only one player is taking an optional action here to sustain the loop. Ask them how many times they want to do it, then tell them to stop.

Okay so we ask the lantern player how many times he wants to do this and he says 10,000 times. Do we really give him 10,000 turns considering the loop can only be performed once per turn?

Edited Brock Ullom (Sept. 2, 2016 03:43:01 PM)

Originally posted by Brock Ullom:

Okay so we ask the lantern player how many times he wants to do this and he says 10,000 times. Do we really give him 10,000 turns considering the loop can only be performed once per turn?

No. You wave your wand and declare all 10000 iterations to have happened. Since we know what the game state looks like, we are going to shortcut to that end state.

Bartłomiej Wieszok
If I have possibility to “revive” not only Mox Opal but also Chromatic Sphere and Chromatic Star? Is it still a loop if I will change what artefact I will put on top of my library each turn?
I think in that case no, but Lantern player still just try to “eat time” there.

edit: On the other hand, I see reasoning like that: I did loop A 4 times, loop B 6 times and loop C one time and I can't then do loop A again therefore I lose.

In fact, it's even simpler than that. The player took some action that returned the game to its original state. You don't really care what happened in the black box because you put in one state, and it spit out the same state. (Remember, in Modern, graveyard order isn't a thing.) The player can fill the black box with whatever he wants, but if it returns to the original state, that's that.

In Legacy, where graveyard order actually counts, you have to get a bit more abstract, but basically the gist of it is that the player can probably rearrange his graveyard, but nothing else. We can shortcut through the mechanics required to achieve this as long as we can demonstrate that the player can put any of some subset of artifact on top of the graveyard. So let the player pick the end state, and that's the end state. No diving back into the loop to rearrange again.

With this situation I see nothing wrong with the lantern player repeating his action on his turn each turn to keep himself from loosing as long as he does so quickly. The idea that we should step in here seem opposed to the general philosophy of the game. Each of his plays is legal both on his and his opponents turn. So I think we should let the play on even if each turn takes 5 seconds. In essence both players are in a no win situation but neither is forced to loose either by and rules in the comp rules document or the mtr. And as long as each player takes their turn quickly I don't see anything in the ipg that applies. It may be boring to watch and even play but each time the latern player adds a card to their library they are advancing the game state. In theory the player with the platinum angel could just as easily be guilty of slow play if they don't pass the turn back right away.

Originally posted by Joshua Feingold:

In fact, it's even simpler than that. The player took some action that returned the game to its original state. You don't really care what happened in the black box because you put in one state, and it spit out the same state. (Remember, in Modern, graveyard order isn't a thing.) The player can fill the black box with whatever he wants, but if it returns to the original state, that's that.

Each time the library goes from having 0 cards in it to having one the game state is being advanced.